Have Kenmore 110.96576200 dryer, have replaced heater box #27983 and upper limit thermostat #3390291, have no power to either device. Where to now?? Dryer vent is open and clear.

Did you use a meter to wire it up? If you did then you would have no problems. How did you test the components? New parts can be bad, too. Manuals: (Follow wiring diagrams with a meter.) https://dl.dropboxusercontent.com/u/8010163/Whirlpool%20Dryers.zip